7: Endocrine Physiology
- Page ID
- 117722
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 7.1: Objectives
- This page outlines learning objectives on physiological regulatory mechanisms, emphasizing signaling pathways and hormone functions. Key topics include distinguishing autocrine, paracrine, and endocrine signaling, comparing neural and endocrine systems, and exploring G-protein roles. It highlights the hypothalamus and pituitary gland's roles in hormone secretion and discusses functions of hormones like oxytocin and growth hormone, as well as mechanisms regulating calcium and glucose levels.
- 7.2: Introduction
- This page covers the endocrine system, detailing the functions of glands and organs that produce hormones crucial for physiological regulation. It emphasizes hormone synthesis, regulation, action, and the interactions between glands, receptors, and target tissues in maintaining homeostasis. The chapter also addresses hormonal feedback loops, adaptations to bodily conditions, and the impact of hormonal imbalances, along with the mechanisms of hormone action and signaling pathways.
- 7.3: Chemical Signaling
- This page details different chemical signaling modalities: autocrine (cell responding to its own signals), paracrine (affecting nearby cells), endocrine (hormones released into the bloodstream for distant effects), and neuroendocrine (linking nervous and endocrine systems). It contrasts the rapid, localized actions of the nervous system with the slower, broader regulatory functions of the endocrine system, which play crucial roles in homeostasis and stress responses.
- 7.4: Endocrine Glands
- This page describes the endocrine system as a complex network of glands that secrete hormones to regulate various physiological functions, including growth and metabolism. It emphasizes the roles of major glands like the hypothalamus, pituitary, thyroid, and pancreas, with the pancreas highlighted for its dual function in digestion and hormone regulation. The summary also notes the contributions of organs such as the heart and kidneys, underscoring the intricate complexity of the system.
- 7.5: Types of Hormones
- This page explains the classification of hormones into three groups: amine, peptide, and steroid hormones. Amine hormones are derived from amino acids, including melatonin and thyroid hormones. Peptide hormones, like insulin, are formed from amino acid chains, while steroid hormones come from cholesterol and include reproductive hormones.
- 7.6: Hormone Transportation
- This page explains how hormones are transported in the body based on solubility. Water-soluble hormones circulate in the bloodstream and use membrane receptors, while lipid-soluble hormones require binding proteins for transport and can enter cells directly. Binding proteins vary in specificity, notably with thyroid hormones utilizing thyroid-binding globulin.
- 7.7: Mechanisms of Hormone Action
- This page discusses the role of hormone receptors in triggering cellular responses by binding to hormones, with intracellular receptors responding to lipid-soluble hormones and membrane receptors to water-soluble hormones. The signaling pathways for these hormones involve G proteins and second messengers.
- 7.8: Target Cell Response
- This page discusses how hormones impact target tissues by modifying receptor quantity and affinity to achieve specific cellular responses. Upregulation enhances receptor sensitivity, as observed with estrogen in the ovary, while downregulation decreases receptors after extended exposure, as seen with progesterone. It also highlights complex hormonal interactions, including permissive, synergistic, and antagonistic effects among various hormones.
- 7.9: Hyposecretion and Hypersecretion
- This page discusses hormonal regulation disruptions caused by hypo- and hypersecretion disorders in the endocrine system. It explains primary hyposecretion as insufficient hormone production due to internal issues, while secondary hyposecretion is linked to inadequate gland stimulation. In contrast, primary hypersecretion refers to excessive hormone production within a gland, and secondary hypersecretion arises from external factors leading to overproduction and hormonal imbalances.
- 7.10: Regulation of Hormone Secretion
- This page discusses the importance of hormone regulation in preventing imbalances and diseases through reflex mechanisms. It highlights negative feedback loops that inhibit hormone secretion, such as in glucocorticoid regulation, and positive feedback loops that enhance secretion, exemplified by oxytocin during childbirth. Hormonal responses are initiated by humoral and neural stimuli, including ADH for dehydration and stress-induced catecholamine release.
- 7.11: The Pituitary Gland and Hypothalamus
- This page discusses the hypothalamus-pituitary complex's critical role in hormone regulation. The hypothalamus inhibits ADH release, affecting water reabsorption and urine output. The anterior pituitary produces hormones influencing growth, metabolism, and reproduction, such as GH, TSH, ACTH, FSH, LH, and prolactin. These hormones regulate processes like lactation and adrenal function, with the anterior pituitary relying on hypothalamic control through releasing and inhibiting hormones.
- 7.12: The Thyroid Gland
- This page discusses the thyroid gland's production of essential hormones T3 and T4, which regulate metabolism, energy expenditure, and development. These hormones are synthesized in thyroid follicles from iodide and thyroglobulin, with a release mechanism governed by a negative feedback loop involving TRH and TSH. Adequate levels are crucial to prevent disorders like goiter and neonatal hypothyroidism.
- 7.13: The Parathyroid Glands
- This page discusses the parathyroid glands, essential for calcium regulation, which produce parathyroid hormone (PTH) through chief cells. PTH plays a key role in managing blood calcium levels by promoting bone calcium release, renal absorption, and intestinal absorption via calcitriol. Its release is regulated by a negative feedback mechanism tied to blood calcium levels, with low magnesium levels affecting PTH secretion. However, chronic low magnesium can hinder parathyroid functionality.
- 7.14: Vitamin D (1,25-Dihydrocholecalciferol)
- This page discusses the importance of vitamin D for calcium balance, its synthesis and conversion to calcitriol in the body, and regulation by parathyroid hormone (PTH). It highlights how PTH affects calcium absorption and reabsorption, and outlines issues arising from abnormal PTH levels, like hyperparathyroidism and hypoparathyroidism, which impact bone health.
- 7.15: Adrenal Glands
- This page discusses the adrenal glands, located above the kidneys, and their role in stress regulation and homeostasis. The outer cortex produces hormones like cortisol and aldosterone for long-term stress and metabolic function, while the inner medulla releases epinephrine and norepinephrine for immediate responses. Together, they manage physiological and psychological stressors.
- 7.16: The Endocrine Pancreas
- This page discusses the pancreas, highlighting its dual role as an exocrine and endocrine organ, composed mainly of pancreatic acini and islets of Langerhans. It outlines the functions of key hormones insulin and glucagon in regulating blood sugar levels: insulin promotes glucose uptake and inhibits production when sugar levels rise, while glucagon stimulates glucose release when levels drop.
- 7.17: References
- This page includes various academic references and visuals on human physiology, primarily focusing on the endocrine and nervous systems. Key concepts discussed are hormone binding, the hypothalamus-pituitary complex, and calcium regulation, with resources addressing conditions like primary hyperparathyroidism and diabetes management.